EHXIBIT 4.66

                               Eighth Amendment to
               Agreement and Certificate of Limited Partnership of
                 Geodyne Energy Income Limited Partnership III-F

     This Eighth  Amendment to Agreement and Certificate of Limited  Partnership
of Geodyne  Energy  Income  Limited  Partnership  III-F (the  "Partnership")  is
entered into by and between Geodyne Resources,  Inc.  ("Resources"),  a Delaware
corporation,   as  successor  General  Partner,   Geodyne   Depositary   Company
("Depositary"),  a  Delaware  corporation,  as  the  Limited  Partner,  and  all
Substituted Limited Partners admitted to the Partnership.

     WHEREAS,  on March 7, 1990, Geodyne Production Company  ("Production"),  as
General Partner, and Depositary executed and entered into that certain Agreement
and Certificate of Limited Partnership of the Partnership (the "Agreement"); and

     WHEREAS,  on February 25, 1993,  Production  executed and entered into that
First  Amendment  to the  Agreement  whereby  it  changed  (i)  the  name of the
Partnership from  "PaineWebber/Geodyne  Energy Income Limited Partnership III-F"
to "Geodyne Energy Income Limited  Partnership  III-F",  (ii) the address of the
Partnership's  principal  place of  business,  and  (iii)  the  address  for the
Partnership's agent for service of process; and

     WHEREAS,  on August 4, 1993,  Production  executed  and  entered  into that
Second Amendment to the Agreement  whereby it amended certain  provisions to (i)
expedite  the  method  of  accepting  transfers  of Unit  Holders'  Units in the
Partnership  and (ii)  provide  for an optional  right of  repurchase/redemption
which may be exercised by the Unit Holders; and

     WHEREAS,  on August 31,  1995,  Production  executed  and entered into that
Third Amendment to the Agreement whereby it amended certain  provisions to allow
transfers  of Units  facilitated  through a matching  service to the extent that
such  transfers   otherwise   comply  with  Internal  Revenue  Service  transfer
regulations  applicable  to  non-permitted  transfers  for  non-publicly  traded
limited partnerships; and

      WHEREAS,  on  July  1,  1996,  Resources,   as  successor  via  merger  to
Production,  executed and entered into, as General Partner,  that certain Fourth
Amendment  to the  Agreement  of Limited  Partnership  whereby  it  amended  the
Agreement to provide that Resources,  as successor via merger to Geodyne, is the
General Partner of the Partnership; and

     WHEREAS,  on February 5, 2001,  Resources  executed  and entered  into that
certain Fifth Amendment to the Agreement whereby the term of the Partnership was
extended for an additional two years, until March 7, 2003; and

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     WHEREAS,  on February  10, 2003,  Resources  executed and entered into that
certain Sixth Amendment to the Agreement whereby the term of the Partnership was
extended for an additional two years, until March 7, 2005; and

     WHEREAS,  on February 7, 2005,  Resources  executed  and entered  into that
certain Seventh  Amendment to the Agreement  whereby the term of the Partnership
was extended until December 31, 2005; and

      WHEREAS,  Section 2.3 of the Agreement provides that the Partnership shall
continue  in full  force and effect for a period of ten (10) years from the date
of its  Activation  (as  defined in the  Agreement),  provided  that the General
Partner may extend the term of the  Partnership  an  additional  431 days of the
current  two year  period  and for up to two  periods  of two  years  each if it
believes  each such  extension  is in the best  interests of the Unit Holders or
until dissolution prior thereto pursuant to the provisions of the Agreement, and

      WHEREAS,  Resources  as General  Partner has elected to extend the life of
the Partnership through December 31, 2007.

      NOW,  THEREFORE,  in  consideration  of  the  covenants,   conditions  and
agreements herein contained, the parties hereto hereby agree as follows:

      Section 2.3. is hereby amended and restated as follows:

            The  Partnership  shall  continue in force and effect until December
      31,  2007,  provided  that the General  Partner may extend the term of the
      Partnership  for an additional 431 days of the current two year period and
      for an additional one period of two years if it believes such extension is
      in the best  interests of the Unit  Holders,  or until  dissolution  prior
      thereto pursuant to the provisions hereof.

      IN WITNESS WHEREOF, the parties hereto have hereunto set their hands as of
this 27th day of October, 2005.

                                    GEODYNE RESOURCES, INC.,
                                    as General Partner

                                    By:   //s// Dennis R. Neill
                                          ---------------------
                                          Dennis R. Neill
                                          President

                                    GEODYNE DEPOSITARY COMPANY,
                                    as the Limited Partner

                                    By:   //s// Dennis R. Neill
                                          ---------------------
                                          Dennis R. Neill
                                          President

                                    GEODYNE RESOURCES, INC.
                                    as Attorney-in-Fact for all
                                    Substituted Limited Partners

                                    By:   //s// Dennis R. Neill
                                          ---------------------
                                          Dennis R. Neill
                                          President


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